Immunologic surrogate of protection for inactivated enterovirus 71 vaccines

In the context of vaccines, the immunological surrogate of vaccine-induced protection implies an immunological marker to prevent or reduce frequency or severity of infection or disease (1). The availability and reliability of such surrogates of protection often play an important role in the development, evaluation, licensure, or utilization of vaccines. World Health Organization (WHO) recommend using the term “surrogate” to mean a vaccine-induced immune response (either humoral or cellular immune) that predicts protection against clinical endpoints, and can be expected to predict vaccine efficacy in vaccine clinical trials (2).